1. Which is longest river in world ?

Answer: Nile, Africa

2. What is the name of tallest Animal ?

Answer: Giraffe

3. Which is Largest Dome in World ?

Answer: St. Peter's Basilica (Rome)

4. Which is highest dam in world ?

Answer:

Jinping-I Dam - 305 m (1,001 ft) in China on Yalong river.
Second Highest is Nurek Dam 300 m (980 ft) Tajikistan on Vakhsh river.

5. Which is Longest road tunnel in the World ?

Answer: Lærdal Tunnel (Norway - 24.51 kilometre)

6. Which is largest continent ?

Answer: Asia

7. Which is Largest library in the world ?

Answer: United State Library of Congress, Washington D.C.